Endorectal ultrasonography using a 7 mHZ probe was performed in 99 patients with a negative history for surgery of the prostate and either findings on rectal examination suggestive of cancer (T3 stage excluded) or a serum level of prostate-specific antigen of 2.5 mg/ml or more. A biopsy gun was used to harvest 1.5 centimetre long specimens. Ultrasound-guided biopsies were performed in peripheral hypoechogeneic areas; in addition, regardless of the result of the endorectal ultrasonography, routine multiple ultrasound-guided biopsies were performed in both lobes of the prostate (3 per lobe). Morbidity consisted in two cases of prostatitis (2%). Among the 99 patients, ultrasound guided biopsies found 16 carcinomas (16.1%), and routine multiple ultrasound-guided biopsies found 32 (32.3%) carcinomas. Four patients with normal results upon rectal examination and endorectal ultrasonography were found to have carcinoma of the prostate. These findings suggest that the morbidity of routine multiple ultrasound-guided biopsies is low; that routine multiple ultrasound-guided biopsies is more sensitive than ultrasound guided biopsies, with 16/99 (16%) additional carcinomas detected in this study and 56% of carcinomas among those patients with findings upon the rectal examination suggestive of malignant disease; and that routine multiple ultrasound-guided biopsies can allow the detection of carcinomas responsible for isolated elevation of prostate-specific antigen levels without anomalies of the rectal examination or endorectal ultrasonography (8% of the carcinomas in this study).